If you liked the Canon 50mm 1.4 (which is one of my favs) you should try the Canon 28mm 1.8. I have a 24-70 2.8L which is a wonderful lens...just too darn heavy on the shoulder mount or Blackbird so I went to the local camera shop and they handed me the 28 1.8. It's about the same size and weight as the 50mm and has the same look to the image which was awesome. Best part is it's $450.

If you have a choice between EF-S 17-55mm f/2.8 IS and the Tokina 11-16mm, what would you take for shooting wide and also using it on stabilizer ?
I guess if IS is not important on stabilizers when shooting wide then Tokina 11-16mm has the upper edge .

This is a great lens. I used it this weekend on a 7D set atop a Merlin rig - absolutely wonderful for Steadicam work. Set focus to about 8' and everything is in focus from 3' to 120 some (infinity for the job I was on). Very nice. Not as fast as the 24, obviously, but very wide. I got some great footage about 3" from a drum kit. Spendy, but very nice. Would be amazingly wide on a 5D...